Explosive nucleosynthesis of ultra-stripped Type Ic supernovae: application to light trans-iron elements

Abstract We investigate the nucleosynthesis that occurs during the two-dimensional neutrino-driven explosion of ultra-stripped Type Ic supernovae evolved from 1.45 and 1.5 M⊙ CO stars. These supernovae explode with an explosion energy of ∼1050 erg and release ejecta of mass ∼0.1 M⊙. The light trans-iron elements Ga–Zr are produced in the neutrino-irradiated ejecta. The abundance distribution of these elements has a large uncertainty because of the uncertainty of the electron fraction of the neutrino-irradiated ejecta. The yield of the elements will be less than 0.01 M⊙. Ultra-stripped supernovae and core-collapse supernovae evolved from a light CO core could be the main sources of light trans-iron elements. They could also produce the neutron-rich nuclei 48Ca. Ultra-stripped supernovae eject ∼0.006–0.01 M⊙ of 56Ni. If most of the neutrino-irradiated ejecta is proton-rich, 56Ni will be produced more abundantly. The light-curves of these supernovae indicate a subluminous fast-decaying explosion with a peak magnitude of about −15 to −16. Future observations of ultra-stripped supernovae could constrain the event rate of a class of neutron star mergers.